Air source heat pumps have become a formidable rival for geothermal heat pumps following the introduction of new variable speed compressor technology, which radically expands the range of temperatures at which they can effectively operate.

Last year, key manufacturers such as Waterfurnace Renewable Energy and LSB Industry subsidiary Climate Master managed to achieve major breakthroughs in efficiency via the incorporation of variable speed compressors into their heat pump systems. While the new technology can be incorporated into both geothermal heat pumps and air source heat…